For whatsoever soil the plant stands in, such is the fruit it bears; if in a sandy and salty soil, of like nature is its fruit; if in a sweet and rich one, it is again similar. So the matter of instruction is a sort of fountain. Teach him to sing those psalms which are so full of the love of wisdom. When in these you have led him on from childhood, by little and little you will lead him forward even to the higher things.